From the prior art spread mooring systems for vessels such as floating storage offloading (FSO) or floating production storage offloading (FPSO) vessels or in general, floating offshore units are known.
WO2010084420 discloses a method and system for tensioning a function line in particular a mooring line of a FPSO vessel. Such a traction method for an operating line, in particular a mooring line, includes the steps of: attaching an end chain portion of the operating line to a socket of a main cable running through a sheave at a work station; reeling in the main cable, using a winch, to bring the socket of the main cable up to the sheave; locking the operating line with a chain stopper; slackening the main cable and moving the sheave closer to the chain stopper to reduce pull on the main cable; reeling in the main cable to run the socket of the main cable through the sheave,—once the socket of the main cable has run through the sheave, releasing the operating line from the chain stopper, and reeling in, by means of the winch, the main cable and the operating line connected to it.
WO2004050470 discloses a mooring windlass/winch system that provides a horizontal shaft type windlass wildcat integral with a wire rope type winch mounted above and behind the windlass wildcat. The combined windlass/winch is mounted on a circular foundation that permits the windlass to rotate in the horizontal plane about the centerline of the windlass chain locker. The ability to orient the windlass and winch in the horizontal plane allows a single windlass to serve a number of mooring chains.
Further as shown in FIG. 1, a mooring system 10 is known from the prior art that comprises a (hydraulic) power unit 12, a chain handler 14 and a number of turn-down sheaves 16. The turn-down sheaves 16 are arranged at a side of the vessel 1 for example an FPSO. The power unit 12 is arranged to power the chain handler 14, that is capable of pulling or paying out the individual mooring legs or chains 18. The mooring legs 18 run from the chain handler 14 over each of the turn-down sheaves 16. The chain handler 14 is at a fixed position towards the centerline 2 of the FPSO and away from the turn-down sheaves 16 in such a way that each mooring leg is under a different angle β with the chain handler. Due to the different angles, pulling characteristics on each mooring leg 18 are different, which require a relatively wide power range for the chain handler 14.
It is an object of the invention to overcome the disadvantages from the prior art.